Weighing scales including a platform upon which an individual may stand and a base for housing structure both to support and translate movement of the platform relative to the base to movement of a graduated scale to be read are known. It is also known that the weighing scales may include an optical system whereby light from a source is passed through the graduated scale so that the image of indicium from the graduated scale is reflected by one or more mirrors to a projection screen carried by the platform. The image on the screen is representative of the weight of the individual. A form of the prior art weighing scales of this type may be seen in Grusin et al. U.S. Reissue Pat. No. 28,040, dated June 11, 1974.
While this form of prior art weighing scales overcomes what has been considered to be one of the principal objections to the weighing scales without the foregoing optical system, namely, the difficulty in read-out of weight, either because of the size or legibility of the indicia or inadequate lighting of the indicia, the prior art has the disadvantage that frequently inaccuracy is introduced to the read-out of weight because of deformation of the base structure upon which the source of light and the graduated scale are independently supported relative to the base. This problem becomes more prevalent through the mass production of weighing scales required to meet commercial demands and, although the deformation may be small, the magnification of the indicia of weight by the optical system can lead to non-negligeable errors in the read-out at the projection screen.